A boy was born for a man among us, and the man named him Al-Qasim. We said to him, "We will not call you Abu-l-Qasim, nor will we respect you for that." The Prophet (ﷺ) was informed about that, and he said, "Name your son `Abdur-Rahman."
Sahih al-Bukhari Book 78, Hadith 210
← Previous Hadith That he and Abu Talha were coming in the company of the Prophet (towards Medina), while Safiya (the Prophet's wife) was riding behind him on his she-camel. After they had covered a portion of the way suddenly the foot of the she-camel slipped and both the Prophet (ﷺ) and the woman (i.e., his wife, Safiya) fell down. Abu Talha jumped quickly off his camel and came to the Prophet (saying.) "O Allah's Messenger (ﷺ)! Let Allah sacrifice me for you! Have you received any injury?" The Prophet (ﷺ) said, "No, but take care of the woman (my wife)." Abu Talha covered his face with his garment and went towards her and threw his garment over her. Then the woman got up and Abu Talha prepared their she-camel (by tightening its saddle, etc.) and both of them (the Prophet (ﷺ) and Safiya) mounted it. Then all of them proceeded and when they approached near Medina, or saw Medina, the Prophet (ﷺ) said, "Ayibun, taibun, `abidun, liRabbina hamidun (We are coming back (to Medina) with repentance, worshiping (our Lord) and celebrating His (our Lord's) praises". The Prophet (ﷺ) continued repeating these words till he entered the city of Medina.

Sahih al-Bukhari Book 78, Hadith 209 Next Hadith → A man among us begot a boy whom he named Al-Qasim. The people said, "We will not call him (i.e., the father) by that Kuniya (Abu-l-Qasim) till we ask the Prophet (ﷺ) about it. The Prophet (ﷺ) said. "Name yourselves by my name, but do not call (yourselves) by my Kuniya."

Sahih al-Bukhari Book 78, Hadith 211